Field of the Invention
The invention relates to an air intake device for an internal combustion engine, including a collector communicating with the outside air through a throttle flap intake port, at least four suction pipes connected to the collector, an intermediate collector formed by an auxiliary body and by portions of the suction pipes, the portions having main orifices for communicating with the auxiliary body and secondary orifices for communicating with one another, and a pivotably mounted wing flap having three wings which open the main orifice and the secondary orifice in an end position, and close off both the main orifice and the secondary orifice in a closing position.
The structure of the air intake device for an internal combustion engine has an appreciable influence on the filling of the cylinders with air. Systems with vibrational charging utilize the flow dynamics of the suction pipes in order to optimize the filling process. At low engine speeds, better filling and therefore a higher torque can be achieved due to long suction pipes, whereas at high engine speeds, the suction pipes must be made short for that purpose.
An air intake device for an internal combustion engine which is known from UK Patent Application GB 2 210 665 A has a collector which is connected to the outside air through an intake port. Four cylinders of the internal combustion engine are connected to the collector through suction pipes. The suction pipes are disposed, in one portion, around a cylindrical auxiliary body and have orifices leading thereto. Inside the auxiliary body there is a switching device in the form of a switching roller with four segment-like sealing surfaces which are distributed around the periphery of its inner wall and which have the same curvature as the inner wall of the auxiliary body and bear on that inner wall. The sealing surfaces are disposed in such a way that they can be brought into two positions as a result of a rotational movement about the longitudinal axis of the auxiliary body. In an end position, the suction pipes can communicate with one another through the orifices, and in a closing position, the sealing surfaces close off the orifices to the suction pipes.
On one hand, when the sealing surfaces are in the closing position, the suction pipe length corresponds to the length which is effective for the air flow. On the other hand, when they are in the end position, strong air turbulence occurs in the region of the auxiliary body and the flow breaks away. The suction pipes communicate through the auxiliary body and thus form an intermediate collector together with the auxiliary body. It is only the length of the suction pipes from the auxiliary body to the cylinders which then has any bearing on the effects of the flow dynamics in terms of the cylinders.
The sealing surfaces, when in the end position, must open the orifices completely. The diameter of the auxiliary body must therefore be dimensioned in such a way that the inner wall surfaces of the auxiliary body between the orifices are large enough to receive the sealing surfaces. Thus, if the circumference of the auxiliary body is minimized, the suction pipes have to be disposed uniformly around the circumference of the auxiliary body. The structural volume is therefore relatively large and the configuration of the suction pipes is subject to narrow limitations.
The orifices can be closed in a sealing manner only if the auxiliary body and the sealing surfaces have a high accuracy of fit, which is only achieved at a very high outlay, in the case of auxiliary bodies injection-molded from plastic. Even a minimal gap of about 0.1 mm between the sealing surfaces and the inner wall of the auxiliary body leads to strong air turbulence and therefore to a significant reduction in the effective suction pipe length.
If the sealing surfaces are made from elastic material, they are exposed to high shearing forces during rotation, which lead to rapid wear of the sealing surfaces. They are therefore subject to high wear.
The drive for the switching device must be constructed to be high-powered, in order to overcome the frictional forces between the inner wall of the auxiliary body and the sealing surfaces.